Safety device for punch presses



Sem. M, w35.' P. E. BOYD SAFETY DEVICE FOR PUNCH PRESSES Filed July 24,1933 #WE/v faq- UNITED STATES YPATENT OFFlCE SAFETY DEVICE FOR PUNCHPRESSES Percy E. Boyd, Detroit, Mich.

Application July 24, 1933, Serial No. 681,957

'7 Claims. v(01.192-24) It is a well known fact that there has alwaysexisted a great difficulty with the operation of punch presses ingeneral, which not only increases `the cost of operating and maintainingthis class of machinery, but the diiiculty is likewise unreliable anddangerous for the operator.

As the press begins to wear after prolonged use and due to the presentconstruction, the square corners of the jaws of the bull gear andlikewise the jaws of the clutch head of the'press become rounded fromrepeated engagement of these elements, and the corners of the jaws ofthe clutch being rounded will have a tendency to engage the jaws ofthebull gear continually when the latterris idling and with a ypronounced.

clattering or pounding eiect, thereby causing a rapid wear and roundingof Aall corners of both sets of jaws, and to an extent whereby all ofthe jaws must be removed and replaced with new ones, which requiresconsiderable delay and expense at regular intervals for this purpose.

With this difliculty also, the crank of the press will not be caused tostop precisely at high dead center, as it should do when the same isoperating correctly, on the contrary the crank will stop approximatelyfrom ve to-fteen degrees before high dead center is reached. Thiscondition prevailing the crankwill have the tendency to, andl veryfrequently does drop to low dead center, simultaneously operating thepress at an unex- ,pected time'and without warningY to the operator,

and if the operators hand would happen to be near the dies a seriousaccident could not be averted.

The principal object of thisinvention is to provide a device that iscoordinatedwith the trip mechanism of the press, for the purpose ofretaining adequate clearance intermediate the jaws of the clutch headand the jaws of the bull gear at all times when 'the press is idling,and as the square cornersvof both sets of jaws begin to Wear,

Van adjustment is pro-vided to overcome the extent of this worncondition, which is in a positive manner so that the press will operatesmoothlyY with safety and greatly prolong the life of the jaws,`therebyeffecting a decided economy in repeated loss of time and expense in thegeneral o-peration and maintenance of this class of machinery.

The invention possesses further'advantag'es, all of which will beobviously apparent during the vcourse of the following detaileddescription, illustrated throughout `the accompanying drawing, Yand morefully pointed out in the appended claims.. Y Y

'end of coil spring 8.

With reference to the drawing:

Figure 1 is a reduced View of a portion of a punch press showing thesame equipped with the device and indicating the proper clearanceintermediate the jaws of the clutch head and the jaws 5 of the bullgear.

Figure 2 is a similar reduced sectional view, showing lthe device in theact of releasing the jaws of the clutch head from those of the bullgear. Y 10 Figure 3 is a front elevation of the device and showing thesame secured to the trip bracket of the press.

Figure 4 is Y a full size longitudinal section through the center of oneof the principal units 15 of the device. l

Figures 5, 6 and 'l are greatly enlarged sections of both sets of jawsof the press, and Figure 5 clearly indicating the sharp corners of thejaws when they are new and Vnot worn; Figure 6 dis- 20 'closes a worncondition of the jaws, and Figure 'l shows an advanced state of wornjaws, or approximately the limit to this extent.

In the following the letters will indicate various Yelements of thepress, while the numerals will 25 have reference directly to therespective portions V which is adapted to engage a similar threaded'aperture 3 within machined face A of press frame B. `The opposite endof said stud also has an externally threaded portion as at fl, which is'adapted to engage a similarly threadedv elongated 40 sleeve 5, withpreferably a castellated nut 6 where clearly indicated in Figure 4.

It is Valso observed that sleeve Eis provided with flanged head l so asto accommodate one Said spring is operatively 45 disposed over stud l,the opposite end of the spring bearing upon freely disposed collar 9upon the said stud. Trip bracket C is a part of the press and is alteredfor coordination with the Vinvention by providing openings Illtherethrough, 50 and said openings being of a somewhat greater diameterthan studs l so as to accommodate the tilting motion of the bracketrelative to press frame l5N duringthe operation ofthe device. said studsbeing permanently xed with frame B. 55

Referring to Figures 5, 6 and '7, D indicates the jaws of clutch head E,and F likewise indicates the jaws of bull gear G, and in Figure 1 theportion of the press shown in the view indicates a press having new jawsin the clutch head and bull gear and normally having sharp corners asshown in Figure 5. In Figure 2 trip bracket C is shown actuating cam Hand in the act of releasing or disengaging jaws D from jaws F. It is tobe understood that when jaws D and F are new and with sharp corners,coil springs 8 are closely compressed, and in the degree that both setsof said jaws become worn, as for example the illustration in Figure 6,the compression of springs 8 is released by backing nuts S of the fourunits uniformly, thereby releasing the respective sleeves 5 which opposethe tension of said springs. The major purpose of springs 8 is toprovide therein ample tension to resist or overcome the tension ofsprings J within clutch head E, and in this manner and with the properadjustment of springs 8, consistent with the worn condition of jaws Dand F, springs 8 will positively cause clutch head E to be positivelyand promptly disengaged from bull gear G at the precise instant whencrank K of crank shaft L is at high dead center; thus the press issafely in a neutral position while bull gear G remains idling. Inaccomplishing this purpose ample clearance is obtained intermediate jawsD and F at all times when the press is neutral and said bull gearidling.

In the normal operation of the press it is understood that cam Hautomatically disengages the clutch by virtue of its operative relationwith roller N, and when the press is idling the jaws of the clutch headand the jaws of the bull gear are positively cleared as in Figure l. Ifthe jaws are worn there is nothing to prevent the jaws of the clutchhead from lagging against the jaws of the bull gear and trying to forceentrance therein because of the pressure exerted upon the clutch headjaws by springs J. Inasmuch as springs 8 are compressed to maximumtension when the jaws are new and unworn, and that they are very muchmore powerful than springs J, in this condition there is a xed relationbetween the tension of both sets of springs referred to, and it is hereto be emphasized that this relation is disturbed in the degree that thejaws are worn. As the jaws wear springs J become elongated, tending toforce jaws of the clutch' head to meet jaws of the bull gear,consequently it is necessary to release springs 8 by backing olf nuts 6,thereby releasing sleeves l, so that springs 8 will compensate for thechanged tension of springs J brought about by the wearing of the clutchjaws, and in this manner the relation between the tension of springs 8and springs J will be maintained same as when the jaws are new aspreviously described.

In the use of this device the press becomes dependable, accurate andsafe at all times, which is an important improvement and advantage inthe operation of the same.

Another marked advantage of the invention is that in view of the extremesimplicity thereof, the same may be installed in connection with thepress for a remarkably low cost in time and material, and the inventionbeing very substantial in construction, the same should satisfactorilyendure for an indenite period, consequently effecting a decided savingin tima-material and delay.

It may be Well to state herein that the invention is a proven discovery,in that several presses .of said studs, the unxed end of said studs havebeen equipped with this device and have been in continuous operation fora period of eighteen months, and upon examination of jaws D and F it wasrevealed that the square corners of the same were almost intact, or freefrom 5 wear, and during the entire period all clattering or pounding ofthe jaws as previously explained, was unknown.

It is of course further understood that wearing of the corners of jaws Dand F is occasioned 10 by reason of worn elements of the press, such asroller N and cam H, and in this worn condition the customary tripbracket used fails to disengage jaws D from jaws F to provide a properclearance between both sets of jaws when the press is neutral,consequently jaws D will have the tendency to engage jaws F, but can notengage any more than to pound until the press is tripped in a normalmanner.

Under the burden of strenuous operation of punch presses it is knownthat both sets of jaws were subjected to such severe wear that it becameactually necessary to install new jaws in both the clutch head and bullgear at regular intervals of two months during the period of suchstrenuous activity. It is needless to add that this was accomplished ata great cost in time and material with the ensuing delay necessary forthis purpose.

The bracket C will assume the tilted position shown in Figure 2 of thedrawing due to the fact that the lowermost pair of coil springs 8 willbe compressedY before the upper pair of coil springs are compressed,when the cam H is actuated by the trip mechanism to release the jaws ofthe clutch head from engagement with the jaws of the bull gear.

Having thus described my invention, what I claim as new is: Y

1. In combination with the trip bracket of a punch press, four principalunits, each of said units comprising an elongated stud, one end of saidstud being adapted to `threadedly engage the frame of the press and bedisposed at right angles thereto, yieldable means whereby said studs arecoordinated with said bracket, for purpose of providing a clearancebetween the clutch head and the bull gear after their release.

2. In combination with the trip bracket of a punch press, four principalunits, each of said units comprising a stud, said studs beingpermanently xed with the frame of the press, a sleeve for each of saidstuds, said sleeves threadedly engaging the outer end portions of saidstuds respectively, the aforesaid bracket having 50 openings for thepassage of said studs respectively, and yieldable means intermediate theaforesaid sleeves and bracket for returning the latter to normalposition after operation of the tripl. ping mechanism of the press.

3. In combination with the trip bracket of a punch press, four principalunits, each of said units comprising a stud that is permanently xed withthe frame of the press, a sleeve for each 5 threadedly engaging saidsleeves respectively, said bracket having openings, said studs adaptedto pass freely through said openings, a collar freely disposed upon eachof said studs, said collars being adjacent the aforesaid bracket, aspring mounted upon each of aforesaid studs, said spring beingintermediate the aforesaid sleeve and collar, means for adjusting thetension of said springs, said means comprising a nut threadedly engagingthe outer end of each of aforesaid studs.

4. In combination with the trip bracket of a punch press, a plurality ofunits adapted to be coordinated with the trip bracket, each of saidunits comprising a stud permanently fixed with the face of the pressframe, a nut, sleeve, spring and collar for each of said studs, saidcollars mounted upon said studs adjacent said trip bracket, said sleevesthreadedly engaging the free ends of said studs, said nuts threadedlyengaging the said studs and adjacent said sleeves and upon the eXtremefree ends of the studs, said springs being interposed between saidsleeves and collars, the specific relation of the elements namedconstituting means in cooperation with the aforesaid bracket forproviding clearance between the clutch head and the bull gear of thepress after same has been normally operated,

5. The combination with the frame, bull gear, clutch head, including thecoacting jaws associated therewith, and the trip mechanism including themovable trip bracket, of a punch press; of yieldable means associatedwith the frame and the trip bracket for assisting in the releaseV of theclutch head from the bull gear and maintaining said coacting jaws clearof one another when the press is idling said yieldable means includingstuds projecting outwardly from the frame through the movable bracket,and coil springs encircling the outer end portions of the studs andbearing against the trip support bracket.

press; of yieldable means associated with the 5 frame of studsprojecting outwardly from the frame and passing freely hrough theaforesaid bracket, a member threaded on the outer end of each stud, anda coil spring encircling the projecting portion of each stud and bearingagainst the movable bracket, said coil spring assisting in l the releaseofthe clutch head from the bull gear and maintaining clearance betweenthe coacting jaws when the press is idling.

7. The combination with the frame, bull gear, clutch head, includingthecoacting jaws associated therewith, and the trip mechanism including themovable trip bracket, of a punch press; of yieldable means associatedwith the frame of studs projecting outwardly from the frame and passingfreely through the aforesaid bracket, a member threaded on the outer endof each stud, a longitudinally adjustable member secured on the outerend of each stud, a collar freely disposed upon each stud adjacent thebracket, and a coil spring encircling each stud and interposed betweensaid adjustable member and the collar for normally assisting in therelease of the clutch head from the bull gear and maintaining clearancebetween the coacting jaws when the press is idling. Y

PERCY E. BOYD.

